import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:miaoji_zhang/features/home/pages/transaction_edit_page.dart';
import 'package:miaoji_zhang/shared/api/api_client.dart';
import 'package:miaoji_zhang/shared/api/business_api.dart';
import 'package:miaoji_zhang/shared/services/current_ledger_store.dart';
import 'package:miaoji_zhang/shared/services/local_database.dart';
import 'package:miaoji_zhang/shared/services/screenshot_channel.dart';
import 'package:miaoji_zhang/shared/services/session_store.dart';
import 'package:miaoji_zhang/shared/services/shanghai_time.dart';
import 'package:miaoji_zhang/shared/services/transaction_events.dart';
import 'package:miaoji_zhang/shared/theme/app_theme.dart';
import 'package:miaoji_zhang/shared/widgets/app_controls.dart';
import 'package:shared_preferences/shared_preferences.dart';

class RecognitionImportService {
  RecognitionImportService._();

  static Future<void>? _activeImport;
  static bool _rerunRequested = false;

  static Future<void> configureNativeContext() async {
    final session = SessionStore.instance;
    final preferences = await SharedPreferences.getInstance();
    if (preferences.getBool('ai_batch_consent_v2') != true) {
      await ScreenshotChannel.setRecognitionToggle('ai_screenshot', false);
    }
    await ScreenshotChannel.configureRecognitionContext(
      hasAccount: session.isAccount,
      aiAllowed: session.aiEnabled,
      baseUrl: ApiClient.baseUrl,
      token: session.isAccount ? await ApiClient.instance.readToken() : null,
    );
  }

  static Future<void> importAutomatic() {
    if (!SessionStore.instance.hasSession) return Future.value();
    final active = _activeImport;
    if (active != null) {
      _rerunRequested = true;
      return active;
    }
    final operation = _runAutomaticImports();
    _activeImport = operation;
    return operation.whenComplete(() {
      if (identical(_activeImport, operation)) _activeImport = null;
    });
  }

  static Future<void> _runAutomaticImports() async {
    try {
      do {
        _rerunRequested = false;
        await CurrentLedgerStore.instance.ensureLoaded();
        final candidates = await ScreenshotChannel.drainRecognitionCandidates();
        final automatic = candidates
            .where((item) => item.canAutoImport)
            .toList();
        final batches = <String, List<RecognitionCandidate>>{};
        for (final candidate in automatic) {
          final batchId = candidate.batchId;
          if (batchId == null || batchId.isEmpty) continue;
          batches.putIfAbsent(batchId, () => []).add(candidate);
        }
        for (final entry in batches.entries) {
          await _importBatch(entry.key, entry.value);
        }
        for (final candidate in automatic.where(
          (item) => item.batchId == null || item.batchId!.isEmpty,
        )) {
          await _import(candidate);
        }
      } while (_rerunRequested);
    } finally {
      _rerunRequested = false;
    }
  }

  static Future<void> handleAction(
    BuildContext context,
    Map<String, dynamic> action,
  ) async {
    final kind = action['action']?.toString();
    if (kind == 'ready') {
      await importAutomatic();
      return;
    }
    if (kind == 'recognition_batch_review') {
      await importAutomatic();
      if (!context.mounted) return;
      final batchId = action['batchId']?.toString();
      context.push(
        Uri(
          path: '/recognition-batches',
          queryParameters: batchId == null || batchId.isEmpty
              ? null
              : {'batchId': batchId},
        ).toString(),
      );
      return;
    }
    if (kind == 'recognition_undo') {
      final transactionId = (action['transactionId'] as num?)?.toInt();
      final candidateId = action['candidateId']?.toString();
      if (transactionId == null || candidateId == null) return;
      try {
        await TxApi.delete(transactionId);
        await ScreenshotChannel.acknowledgeRecognitionCandidate(
          candidateId,
          'undone',
        );
        TransactionEvents.notifyChanged();
        if (context.mounted) {
          ScaffoldMessenger.of(
            context,
          ).showSnackBar(const SnackBar(content: Text('已撤销这笔智能识别账单')));
        }
      } catch (error) {
        if (context.mounted) {
          ScaffoldMessenger.of(
            context,
          ).showSnackBar(SnackBar(content: Text(apiErrorMessage(error))));
        }
      }
      return;
    }
    if (kind == 'recognition_edit') {
      final transactionId = (action['transactionId'] as num?)?.toInt();
      final cached = transactionId == null
          ? null
          : LocalDatabase.instance.transaction(transactionId);
      if (!context.mounted) return;
      if (cached == null) {
        ScaffoldMessenger.of(
          context,
        ).showSnackBar(const SnackBar(content: Text('这笔账单尚未同步到本机，请稍后重试')));
        return;
      }
      final updated = await Navigator.of(context).push<TxItem>(
        MaterialPageRoute(
          builder: (_) =>
              TransactionEditPage(transaction: TxItem.fromJson(cached)),
        ),
      );
      if (updated != null) TransactionEvents.notifyChanged();
      return;
    }
    if (kind != 'recognition_confirm' || !context.mounted) return;

    await CurrentLedgerStore.instance.ensureLoaded();
    final candidates = await ScreenshotChannel.drainRecognitionCandidates();
    if (!context.mounted) return;
    final requestedId = action['candidateId']?.toString();
    final candidate = candidates.where((item) {
      return item.state == 'pending_confirm' &&
          (requestedId == null || item.id == requestedId);
    }).firstOrNull;
    if (candidate == null) {
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(const SnackBar(content: Text('这条识别结果已处理或已过期')));
      return;
    }
    final confirmed = await _showConfirmation(context, candidate);
    if (confirmed != true) return;
    try {
      await _import(candidate);
      if (context.mounted) {
        ScaffoldMessenger.of(
          context,
        ).showSnackBar(const SnackBar(content: Text('识别结果已入账')));
      }
    } catch (error) {
      if (context.mounted) {
        ScaffoldMessenger.of(
          context,
        ).showSnackBar(SnackBar(content: Text(apiErrorMessage(error))));
      }
    }
  }

  static Future<TxItem> _import(RecognitionCandidate candidate) async {
    final category = await _resolveCategory(candidate, {});
    final occurredUtc = validOccurredAtUtc(candidate.occurredAtEpochMs);
    final transaction = await TxApi.create(
      categoryId: category.id,
      type: candidate.type,
      amount: candidate.amount,
      note: candidate.merchant?.trim().isNotEmpty == true
          ? candidate.merchant!.trim()
          : (candidate.note ?? '智能识别'),
      paymentMethod: candidate.appName,
      source: candidate.source,
      sourceText: candidate.sourceText,
      occurredAt: ShanghaiTime.toCivil(occurredUtc),
      clientRequestId: candidate.clientRequestId,
      transferDirection: candidate.transferDirection,
      counterparty: candidate.counterparty,
      provider: candidate.provider,
      providerTransactionId: candidate.providerTransactionId,
      recognitionOccurrenceId: candidate.recognitionOccurrenceId,
      evidenceFingerprint: candidate.evidenceFingerprint,
      recognitionConfidence: candidate.identityConfidence,
    );
    await ScreenshotChannel.acknowledgeRecognitionCandidate(
      candidate.id,
      'imported',
      transactionId: transaction.id,
    );
    TransactionEvents.notifyChanged();
    return transaction;
  }

  static Future<void> _importBatch(
    String batchId,
    List<RecognitionCandidate> candidates,
  ) async {
    final categoryCache = <String, List<CategoryItem>>{};
    final drafts = <RecognitionBatchDraft>[];
    for (final candidate in candidates) {
      final category = await _resolveCategory(candidate, categoryCache);
      final occurredUtc = validOccurredAtUtc(candidate.occurredAtEpochMs);
      drafts.add(
        RecognitionBatchDraft(
          candidateId: candidate.id,
          clientRequestId: candidate.clientRequestId,
          categoryId: category.id,
          type: candidate.type,
          amount: candidate.amount,
          note: candidate.merchant?.trim().isNotEmpty == true
              ? candidate.merchant!.trim()
              : (candidate.note ?? '智能识别'),
          paymentMethod: candidate.appName,
          source: candidate.source,
          sourceText: candidate.sourceText,
          occurredAt: ShanghaiTime.toCivil(occurredUtc),
          transferDirection: candidate.transferDirection,
          counterparty: candidate.counterparty,
          provider: candidate.provider,
          providerTransactionId: candidate.providerTransactionId,
          recognitionOccurrenceId: candidate.recognitionOccurrenceId,
          evidenceFingerprint: candidate.evidenceFingerprint,
          recognitionConfidence: candidate.identityConfidence,
        ),
      );
    }
    final transactions = await TxApi.createRecognitionBatch(batchId, drafts);
    if (transactions.length != drafts.length) {
      throw StateError('批次入账结果不完整，请稍后重试');
    }
    for (final candidate in candidates) {
      final transaction = transactions[candidate.id];
      if (transaction == null) {
        throw StateError('批次入账缺少候选 ${candidate.id}');
      }
      final acknowledged =
          await ScreenshotChannel.acknowledgeRecognitionCandidate(
            candidate.id,
            'imported',
            transactionId: transaction.id,
          );
      if (!acknowledged) throw StateError('批次状态确认失败，请稍后重试');
    }
    TransactionEvents.notifyChanged();
  }

  static Future<CategoryItem> _resolveCategory(
    RecognitionCandidate candidate,
    Map<String, List<CategoryItem>> cache,
  ) async {
    if (candidate.type != 'income' &&
        candidate.type != 'expense' &&
        candidate.type != 'transfer') {
      throw StateError('识别结果缺少明确的收支类型');
    }
    if (candidate.type == 'transfer' &&
        candidate.transferDirection != 'in' &&
        candidate.transferDirection != 'out') {
      throw StateError('转账识别结果缺少方向');
    }
    final categoryType = candidate.type == 'transfer'
        ? candidate.transferDirection == 'in'
              ? 'income'
              : 'expense'
        : candidate.type;
    final categories = cache[categoryType] ??= await TxApi.categories(
      categoryType,
    );
    if (categories.isEmpty) throw StateError('当前账本没有可用分类');
    return categories
            .where((item) => item.id == candidate.categoryId)
            .firstOrNull ??
        categories
            .where((item) => item.name == candidate.categoryHint)
            .firstOrNull ??
        categories.where((item) => item.name == '其他').firstOrNull ??
        categories.first;
  }

  static DateTime validOccurredAtUtc(int epochMs, {DateTime? now}) {
    final current = (now ?? DateTime.now()).toUtc();
    final parsed = DateTime.fromMillisecondsSinceEpoch(epochMs, isUtc: true);
    final oldest = current.subtract(const Duration(days: 1));
    final newest = current.add(const Duration(minutes: 5));
    return parsed.isBefore(oldest) || parsed.isAfter(newest) ? current : parsed;
  }

  static Future<bool?> _showConfirmation(
    BuildContext context,
    RecognitionCandidate candidate,
  ) {
    final palette = context.jz;
    return showModalBottomSheet<bool>(
      context: context,
      backgroundColor: Colors.transparent,
      builder: (sheetContext) => SafeArea(
        child: Container(
          padding: const EdgeInsets.fromLTRB(20, 0, 20, 20),
          decoration: BoxDecoration(
            color: palette.card,
            borderRadius: const BorderRadius.vertical(top: Radius.circular(24)),
          ),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              const JzSheetHeader(
                title: '确认识别结果',
                subtitle: '信息来自本机解析，确认后才会写入账本',
              ),
              const SizedBox(height: 14),
              Container(
                padding: const EdgeInsets.all(16),
                decoration: BoxDecoration(
                  color: palette.background,
                  borderRadius: BorderRadius.circular(16),
                  border: Border.all(color: palette.line),
                ),
                child: Row(
                  children: [
                    Container(
                      width: 42,
                      height: 42,
                      decoration: BoxDecoration(
                        color: candidate.isIncome
                            ? palette.primaryBackground
                            : palette.expenseBackground,
                        borderRadius: BorderRadius.circular(13),
                      ),
                      child: Icon(
                        candidate.isIncome
                            ? Icons.south_west_rounded
                            : Icons.north_east_rounded,
                        color: candidate.isIncome
                            ? AppTheme.primary
                            : AppTheme.red,
                      ),
                    ),
                    const SizedBox(width: 12),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text(
                            candidate.merchant ?? candidate.appName,
                            style: TextStyle(
                              color: palette.text,
                              fontWeight: FontWeight.w700,
                            ),
                          ),
                          const SizedBox(height: 4),
                          Text(
                            '${candidate.appName} · ${candidate.typeLabel}',
                            style: TextStyle(
                              color: palette.text2,
                              fontSize: 12,
                            ),
                          ),
                        ],
                      ),
                    ),
                    Text(
                      '${candidate.isIncome ? '+' : '-'}¥${candidate.amount.toStringAsFixed(2)}',
                      style: TextStyle(
                        color: candidate.isIncome
                            ? AppTheme.primary
                            : AppTheme.red,
                        fontSize: 18,
                        fontWeight: FontWeight.w800,
                      ),
                    ),
                  ],
                ),
              ),
              const SizedBox(height: 16),
              Row(
                children: [
                  Expanded(
                    child: JzActionButton(
                      label: '稍后处理',
                      secondary: true,
                      onPressed: () => Navigator.pop(sheetContext, false),
                    ),
                  ),
                  const SizedBox(width: 10),
                  Expanded(
                    child: JzActionButton(
                      label: '确认入账',
                      onPressed: () => Navigator.pop(sheetContext, true),
                    ),
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}